MAPAX™ – The Optimal Solution
of Modified Atmosphere
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Why you should read about
modified atmosphere
Modified Atmosphere Packaging, or MAP, is
a method for extending shelf-life, preserving
the high quality of foodstuffs, and improving
overall cost-effectiveness. It can do all this
because it
4 increases sales by satisfying the growing
demand by consumers for naturally preserved food quality, without additives
and preservatives
4 increases shelf-life quality in the distribution chain by extra days or even weeks,
which increases the availability of fresh
food to consumers
4 reduces the return of spoiled foodstuffs
4 enhances production efficiency and
distribution by cutting costs
4 increases sales volumes because new
products can be offered on new markets.
To achieve these benefits, consideration must
be paid to a number of factors. It is this overall
concept – designated MAPAX™ from AGA
– that is the subject of this booklet. That is
why we recommend that you continue reading.
TM MAPAX is a trademark of AGA AB and is registered or applied for in several countries.
Table of Contents
CONSUMERS
The recipe for protecting food quality ......................................................................................................4 –5
Modified atmosphere gives benefits throughout ....................................................................................6 –7
RESEARCH AND DEVELOPMENT
Natural spoilage must be retarded to keep good quality ....................................................................8 – 9
Modified atmosphere – the most natural way to retain high quality ..........................................10 –11
PACKAGING MATERIALS
Many questions to answer in choosing packaging materials .........................................................12–13
PACKAGING MACHINES
There is a packaging machine for every need .....................................................................................14–15
GAS SUPPLY
A gas supply adapted to every application ..........................................................................................16 –17
THE MAPAX CONCEPT
MAPAX meets varying customer needs for different applications ..............................................18 –19
The right MAPAX solution suitable for:
MEAT AND MEAT PRODUCTS .........................................................................................20 –21
FISH AND SEAFOOD ..............................................................................................................22 – 23
DAIRY PRODUCTS ..................................................................................................................24 –25
FRUITS AND VEGETABLES .................................................................................................26– 27
DRY FOODS AND BAKERY PRODUCTS ......................................................................28 –29
PREPARED FOODS ..................................................................................................................30 –31
FUTURE
Why does MAP represent the food preservation technology of the 90s?..................................32 –33
GLOSSARY ..................................................................................................................................................34 –37
REFERENCE LITERATURE ..................................................................................................................... –38
AGA ADDRESSES .......................................................................................................................................... –39
3
Consumers
The recipe for protecting food quality
4
Savoury stuffed lamb chops, steaming mashed
potatoes, fresh vegetables, mixed salads.... A
decade or so ago, preparing a meal could take
hours. Very soon, one will only have to ponder
the offerings of the nearest store’s chilled-food
counter, turn on the kitchen’s microwave oven
a few minutes – and dinner is ready to enjoy.
The packaging of fresh food, both semiprepared and prepared dishes, have become a
firmly anchored concept in the minds of modern-day consumers. They want to see food on
their plates with the same freshness as when it
was first prepared.
This intensified interest in fresh foodstuffs
is a strong driving force behind the development of new shelf-life-enhancing methods,
whereby artificial additives and preservatives
no longer are acceptable. Nowadays, efforts
are being made to meet consumer demands for
naturally preserved food quality, handled and
processed as little as possible.
MAP – the winning food preservation
technology of the 1990s
Using gases as a preservative method has been
used for more than 50 years to store and distribute animal carcasses and bulk products
such as meats and fruits. A relatively new preservative technology for enhancing the shelf-life
of consumer food products is Modified Atmosphere Packaging (MAP). It utilizes gases in
packaging to maintain quality from the producer to the consumer. MAP has been developed by large-scale food-processors and wholesalers, and it is, internationally, the fastest
growing method for preserving the inherent
quality of foodstuffs. Modified atmosphere
very likely will become the winning method
of the 1990s as a natural way to preserve the
original quality of foodstuffs. In Western
Europe, the number of MAP food products
doubled between 1987 and 1989. The trend
continues as strong during the 1990s.
Contents in brief
4 Consumer demand for fresh foods with naturally
preserved quality leads to new shelf-life-enhancing
methods.
4
MAP technology is expanding rapidly.
5
Consumers
Modi½ed atmosphere
gives bene½ts throughout
By packaging foodstuffs in a modified atmosphere, it is possible to extend high quality and
shelf-life by days or even weeks. Products that
previously could not be stored fresh throughout the distribution chain can now be offered
in shops without sacrificing quality.
High quality boosts sales
For the consumer, modified atmosphere packaging means that product quality will be high
and consistent, so that the assortment in the
food store will be fresh every day of the week.
Maintaining high food quality for a few
extra days or even weeks increases the availability of fresh products to the consumer and
can dramatically boost sales. Examples taken
from the fish industry show that maintaining
quality a few extra days can triple sales.
Reduced spoilage and returns
Fresh food that is not sold in time is returned.
This is a big-scale problem that seriously affects productivity.
MAP makes it possible for products to
retain a safe level of quality. The result is reduced spoilage and fewer returns.
Production and distribution become
more rational and profitable
Enhanced shelf-life quality also means that
production – and the entire logistics chain
from the time that the raw material is brought
6
in until the distribution trucks drive out – can
be arranged more rationally and with greater
flexibility.
The number of deliveries can be reduced,
and the geographical distribution, increased.
Enhanced shelf-life also means that fluctuations in the availability of certain raw materials, due, for instance, to seasonal variations,
can be evened out. Equipment and employment
can be dimensioned for mean production rate
instead of occasional peaks.
Increased profitability – through
completely new products
Modified atmospheres open up new opportunities for the sale of new products on new
markets. MAP makes it possible, for instance,
to offer fresh pizza or ready-mixed salads in
the shops.
Contents in brief
4 Fresh product sales increase dramatically with MAP.
4 An improved economy due to fewer product returns
4
and a more effective production.
It is possible to market new products with great
demand using MAP.
Fresh food in modified atmosphere.
7
Research and development
Natural spoilage must be retarded
to keep good quality
Food is a biological, sensitive substance. Original freshness and shelf-life are affected by
the inherent properties of the product as much
as by external factors.
Internal factors affecting quality are
4 the type and quantity of microorganisms
4 water activity (aw)
4 pH
4 cell respiration
4 food composition.
External factors affecting the inherent quality
are such things as
4 the temperature
4 hygienic conditions
4 gas atmosphere
4 process methods.
It is therefore of critical importance to the
shelf-life how the product is handled in the
High quality shelf-life is
extended when microbial
deterioration is inhibited.
Quality
High
+8 °C
+4 °C
+2 °C
Low
Time
Extra days of high quality shelf-life
8
processing stage, on the filling line or during
chilling prior to packaging.
Spoilage starts immediately
It is primarily microbial and chemical/biochemical deterioration that destroys food.
Microbial deterioration starts immediately
after harvesting or slaughtering. The presence
of microorganisms can be traced to the raw
materials, the ingredients and the environment.
Microorganisms are found everywhere in our
surroundings, e.g. on our skin, on tools and in
the air. For this reason, good hygienic conditions must be maintained throughout the processing chain.
The ways in which microorganisms bring
about spoilage vary depending on the type of
organism and the foodstuff itself.
Basically, microorganisms can be divided
into two categories: aerobic and anaerobic.
Aerobic organisms require the presence of oxygen (O2) to survive and multiple. Anaerobic
organisms, on the other hand, grow in the absence of oxygen.
Aerobic microorganisms include Pseudomonas, Acinetobacter and Moraxella, which
spoils food by decomposing and producing
substances that give bad taste and odour.
Anaerobic microorganisms include
Clostridium and Lactobacillus. Clostridium,
when foodstuffs are handled incorrectly, can
generate a toxin. Lactobacillus, on the other
hand, is a harmless bacterium that turns the
food sour by producing lactic acid.
Low temperature a highly
effective inhibitor
Temperature is one of the most important factors controlling microbiological activity. Most
microorganisms multiple optimally in the 20 to
30 °C range and show reduced growth at lower
temperatures. Careful temperature monitoring is
therefore vital during all food handling and
distribution stages.
Chilling alone, however, will not solve all
microbiological problems. There are some
psychrophilic bacteria, e.g. Pseudomonas, that
multiple at relatively low temperatures. For such
organisms, other defences must be resorted to,
such as a modified atmosphere.
Oxygen causes chemical breakdown
The chemical reactions may be oxidation of
vitamins or lipids or caused by enzymes.
The chemical breakdown of lipids is the primary process in dry or dehydrated foodstuffs
and in high-fat fish. This is due to the oxidation
of unsaturated fats in the presence of atmospheric
oxygen, causing the product to turn rancid.
Relative reaction rate
Lipid oxidation
Enzymatic
activity
Moulds
Yeasts
Bacteria
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Microbiological shelf-life of fresh beef at different
temperatures and atmospheres.
Shelf-life (days)
A = 100% CO2 1 °C
B = Vacuum 1 °C
100
C = 100% CO2 4 -5 °C
D = Vacuum 4-5 °C
75
E = 10-20% CO2
50
F = 15% CO2
25
G = 50-60% CO2
2-10% O2 rest N2 4 °C
40% O2 rest N2 4 °C
40-50% O2 4 °C
H = Air 4 °C
0
A
B
C
D
E
F
G
H
I
I = 100% O2 1-3 °C
Enzymatic reactions caused by, for example,
polyphenol oxidase bring about the browncolouring of sliced fruits and vegetables.
Oxygen is however important in maintaining
the red colour of cut meats.
From food preservation to the
protection of natural quality
Present developments are moving away from the
previous preservative methods that physically or
chemically alter the product toward less severe
methods that leave the product unchanged.
The methods that represent the ultimate
attempt to protect the inherent quality
of a food product extend from
Contents in brief
processes such as high-pressure and
4 Foodstuffs are sensitive products that immediately begin
microwave methods to various
to spoil after harvesting or
packaging techniques, e.g. oxygen
slaughter owing to microbial
absorption, vacuum, sous-vide
and/or physical and chemical
techniques and MAP.
deterioration.
MAP is a natural shelf-life4 Low temperature retards the
deterioration process.
enhancing method that is growing
4 New, less severe preservative
rapidly on an international scale. It
methods protect the original
often complements other methods.
quality of the foodstuffs.
Chemical and biological reaction vs. water activity.
9
Research and development
Modified atmosphere – the most natural
way to retain high quality
mmol CO2 dissolved/Kg H2O
70
60
50
40
30
20
10
0
10 20 30 40 50
Temperature (°C)
CO2 solubility in water.
Solubility in water at Pgas = 100 KPa
litre/kilogram at +20°C.
Argon, Ar
0.033
Hydrogen, H2
0.018
Carbon dioxide, CO2
0.878
Nitrous oxide, N2O
0.610
Nitrogen, N2
0.015
Oxygen, O2
0.030
10
The correct gas mixture in modified atmosphere packaging maintains high quality by
retaining the original taste, texture and appearance of the foodstuff.
The gas atmosphere must be chosen with
due consideration to the particular foodstuff
and its properties. For low-fat, high-moisturecontent products, it is especially the growth of
microorganisms that is to be inhibited. Should
the product, instead, have a high-fat content
and low water activity, oxidation protection is
the most important.
The MAP gas mixtures usually consist of
the normal air gases: carbon dioxide (CO2),
nitrogen (N2) and oxygen (O2). A certain
amount of microorganism growth inhibition
can also be achieved with the help of other
gases such as nitrous oxide, argon or
hydrogen.
Each of the gases has its own unique
properties that affect its interaction with the
foodstuffs. The gases are used in mixed atmospheres having suitable proportions or by
themselves.
Carbon dioxide content
important for results
Carbon dioxide is the most important gas in
the field of MAP technology. Most microorganisms such as mould and the most com-
mon aerobic bacteria are strongly affected by
carbon dioxide. The growth of anaerobic microorganisms, on the other hand, is less affected by
this gas atmosphere.
Carbon dioxide inhibits microbial activity
by effectively dissolving into the food’s liquid
phase, thereby reducing its pH and by penetrating biological membranes, causing changes
in permeability and function.
Nitrogen – inert and stabilizing
Nitrogen is an inert gas. It is primarily used
to replace oxygen in packaging and thereby
prevents oxidation.
Owing to its low solubility in water, nitrogen also helps to prevent package collapse by
maintaining internal volume.
Log n
Air
N2
8
CO2
6
4
0
12
24
36
Days
Bacterial growth on fresh pork in different atmospheres
at +4 °C.
aw
pH
temp
gas (CO2)
CO2 provides an extra hurdle for chilled food safety.
Oxygen level should be as low as possible
For most foodstuffs, the package should contain as little oxygen as possible to retard the
growth of aerobic microorganisms and reduce
the degree of oxidation.
There are, however, exceptions. Oxygen
helps to preserve the oxygenated form of
myoglobin, which gives meat its red colour.
Oxygen is required for fruit and vegetable
respiration.
Contents in brief
4 Gases mainly used in MAP are carbon dioxide (CO2),
4
4
nitrogen (N2) and oxygen (O2).
The unique properties of the gases are utilized in
modified atmosphere packaging.
Carbon dioxide is the most important gas in
preserving product quality for chilled food.
Ulf Rönner, Ph.D., Senior Scientist
SIK, The Swedish Institute for Food
Research, Gothenburg, Sweden
“In future, consumers will demand
food products of high quality that
are natural, fresh and minimally
processed.
The response of food producers
will be to invest in new technologies
to meet this demand.
A possible scenario, in which
MAP has a role to play, may be a
minimal processing of food using
microfiltration, irradiation, ultrasound or high pressure followed by
MAP technology, resulting in
better food safety and shelf-life
compared with today’s products.
Food producers have a need to
better understand the safety margins
of products when a new technology
such as MAP is used.
The main components in stabilizing food with MAP is the use of
gases. The primary gases are CO2,
N2 and O2 either alone or in mixtures.
Carbon dioxide has bacteriostatic
and fungistatic properties and acts as
a preservative in products. The effect
of CO2 is increased at low temperatures because of its enhanced
solubility in water.
The main sites of action for CO2
appear to be the biological membranes and cytoplasmic enzymes
The degree of growth inhibition
offered by CO2 differs widely
depending on the species of microorganisms and environmental
parameters and hurdles such as pH,
aw, salt and sugar.
When applying MAP to food
products, the producer needs to consider many external and internal factors in order to retain high quality
during product storage.”
11
Packaging materials
Many questions to answer
in choosing packaging materials
Packaging materials are of decisive importance
for food quality and shelf-life. Many sophisticated packaging solutions have been developed to prevent rapid deterioration caused by
oxygen, light and bacteria or by foreign odour
and taste substances that come into contact
with the product.
The manufacturer of foodstuffs faced with
choosing suitable packaging designs and materials has many important decisions to make.
What does the product require in the way of
packaging as protection against quality deterioration from microbial growth, oxidation,
dehydration, etc.? What barrier properties does
the packaging provide against oxygen, light
and volatile substances? What water vapour
transmission rate should the packaging have?
What applies with regard to the material’s
transparency, sealing ability, anti-fogging
properties, microwavability or price?
Various material properties combined
Packaging materials used with all forms of
MAP foods (with the exception of fruits and
vegetables) should have high barrier characteristics. Polymers used include polyester, polypropylene, polystyrene, polyvinyl chloride,
nylon, ethylene vinyl acetate and ethylene vinyl
alcohol polymers. These are usually laminated
or co-extruded with polyethylene, which is in
direct contact with the food and is the heatsealing medium.
Research work strives to use environment12
friendly materials both for manufacture and
for subsequent combustion as well as for an
optimization of the packaging material, so
that the amount of material is minimized.
That is why PVC is being replaced more and
more by other materials such as APET or
PS/EVOH and PVdC is being replaced by
EVOH or OPA.
Below is a list of some typical materials
used with products. The exact composition of
the film is adapted to the individual product
and to the type of package required.
In order that a modified atmosphere will
be retained during the lifetime of the package,
several different plastic materials are often
combined into a multi-layered structure, each
layer having its own function (page 13).
Different plastic materials can therefore be
chosen and combined to achieve
4 mechanical strength
4 water vapour barriers to prevent weight
loss and dehydration
4 gas barrier
4 gas permeability
4 anti-fogging properties (the inside of the
material should have a surface that does
not allow the formation of water droplets,
which reduce transparency)
4 sealing properties, i.e. capable of sealing
into a tight package while retaining material properties even along the weld seam.
Primary function of various basic materials
APET.......................rigidity, O2 barrier
CPET.......................rigidity, high temperature
resistance, O2 barrier
EVA......................... sealing layers
EVOH.....................O2 barrier
HDPE......................moisture barrier, rigidity,
microwave capability,
sealing layers
LDPE.......................sealing layers
OPET...................... high temperature resistance,
flexibility, puncture
resistance
OPP......................... moisture barrier, flexibility,
puncture resistance
PA.............................high temperature resistance,
flexibility, toughness, forming
strength, some O2 barrier
PAN........................ O2 barrier
PET.......................... rigidity, some O2 barrier
PP............................. moisture barrier, rigidity,
microwave capability
PS............................. rigidity
PVC......................... rigidity, O2 barrier
PVdC...................... moisture barrier, O2 barrier
Abbreviations
APET............................ amorphous polyester
CPET............................ crystallized polyethylene
terephthalate
EVA.............................. ethylene-vinyl acetate
EVOH.......................... ethylene-vinyl alcohol
HDPE........................... high density polyethylene
LDPE............................ low density polyethylene
Typical multi-film structure
PE
PVdC
PET
Abbreviations cont.
OPET........................... oriented polyethyleneterephthalate
OPP............................... oriented polypropylene
PA.................................. polyamide (nylon)
PAN...............................acrylonitrile
PE.................................. polyethylene (polyester)
PET............................... polyethylene terephthalate
(polyester)
PP................................... polypropylene
PS................................... polystyrene
PVC...............................polyvinyl chloride
PVdC............................polyvinylidene chloride
Contents in brief
4 Properties of materials are important in maintaining
4
4
quality.
Different materials can have different major
properties, such as permeability, mouldability and
puncture strength.
Materials can be combined in to a multi-layered
structure.
13
Packaging machines
There is a packaging machine for every need
There are five main groups of packaging machines used with MAP technology depending
on the type of product. Although these machines are based on different principles, the
basic working operation is the same. First, a
package is formed (or prefabricated packages
are used) and filled with the product. Then,
the air in the package is replaced by a modified
atmosphere. Finally, the package is sealed.
These three steps take place either manually or
automatically.
The methods used to modify the atmosphere
include gas flushing or vacuum extraction and
then gas injection.
In gas flushing, the air inside the package
is replaced by a continuous gas stream that
dilutes the air surrounding the food product
before the package is sealed. Since this dilution is continuous, the packaging rate can
be high.
In the vacuum process, air is extracted
from the package and the resultant vacuum is
broken by injection with the desired gas mixture. Since this is a two-step process, its speed
is slower than that of the gas flushing method.
Because the air is almost totally removed, however, the efficiency of this process with respect
to residual oxygen levels is better than in the
case of gas flushing.
14
Horizontal flow-pack
The foodstuffs are fed into a horizontal flowing tube that is constantly formed by the packaging machine. The tube is sealed and cut off
along both sides of the product. Gas is flushed
into the resultant bag purging the air. This
equipment works fast and uses less complicated film material than the deep-drawing
machine. Typical foods are bakery products,
sausages, cheese, pizza and green salads.
Vertical flow-pack
A film is formed into
a tube that is pinched
together at one end
and sealed over an
injection pipe. The
product is portioned
out into the tube,
which is then sealed at
the other end and cut
off. Gas is continually
being fed through the tube to purge the air.
This machine is mostly used for powdered and
bulk products such as coffee and peanuts as
well as diced foodstuffs.
Deep-drawing machine
Film is heat formed into a tray on a lower
conveyor belt and the product is then added.
Air is extracted, gas injected and the loaded
package is sealed by welding on a film from
an upper conveyor belt. This machine is
suitable for foodstuffs such as meat, fish and
prepared food.
Bag-sealing machine
bag-in-box
Prefabricated bags are
used that are filled with
the product. A snorkel
probe is introduced into
the bag and air is extracted.
Gas is then fed in, the
snorkel is removed, and
the bag is sealed. Such equipment is used for
large packages of, for example, meat, poultry
and fish.
Vacuum
chamber machine
Prefabricated bags or
trays are used into
which the product is
inserted. The packages
are placed in a chamber
from which the air is extracted and the pressure then equalized with gas. The packages are
then sealed by welding. This machine type is
suitable for small production volumes at a
relatively low cost.
Contents in brief
4 Several types of machines are available on the
4
4
market for MAP.
The machine designs are based on two techniques:
gas flushing and vacuum suction followed by gas
injection.
The choice of machine is governed by the packaged
product, the packaging material and the production
volume.
15
Gas supply
A gas supply adapted to every application
AGA supplies the MAP gases: carbon dioxide
(CO2), nitrogen (N2) and oxygen (O2) – either
pre-mixed in cylinders under high pressure or
as separate gases in cylinders or insulated tanks
for subsequent mixing at the packaging machine. The MAP gases are in accordance with
the proposed EEC directive on food additives.
N2 and O2 are separated from the air and
CO2 is taken from natural wells or as a byproduct from, for instance, fermentation processes or ammonia production.
In many cases, it may be more effective and
practical to produce nitrogen on site using PSA
(Pressure Swing Adsorption) or a permeable
membrane plant.
Careful evaluation behind each choice
The supply option that may be best depends on
the type of foodstuff, the production volume,
the packaging line, and also whether the gas is
to be used anywhere else in production.
It may be highly preferable to have premixed gases supplied if production is relatively
limited or if a new production facility is being
started up. When production rates increase,
and if different products are to be packaged, it
may be more suitable and economic to switch
over to mixing gases on site. Then a mixer is
used and the gases are supplied from cylinders,
tanks or PSA/membrane systems.
Each application must be evaluated separ-
16
ately before decisions can be taken regarding
the supply options and gas mixtures. For
quality assurance, regularly checking the gas
mixture in the ready packages after sealing is
recommended.
AGA a reliable supplier
AGA can build a gas centre and network for
the safe, reliable and economic distribution
of gases to the various points of use in a production line or factory. AGA can provide
assistance in gathering data and in conducting
trial runs as well as in full operation and fine
tuning. Owing to its close collaboration with
customers, AGA is often given total responsibility for the supply of gases, including the
building and maintenance of a customer’s internal gas distribution network.
Continuous training of a customer’s personnel and an active participation in a customer’s product and process development is
frequently included.
Contents in brief
4 AGA offers optimal supply methods paying heed
4
4
to such things as production volumes.
The gases are supplied either pre-mixed or for
mixing on site.
AGA assumes total responsibility for the gas supply.
MAPAX™
MAPAX™ meets customer needs
for different applications
MAPAX from AGA can be defined as an
optimal gas mixture and gas supply based on
the necessary data about foodstuffs, gases and
packaging.
MAPAX takes into consideration:
4
4
4
4
4
4
the handling and processing of the product
the types and quantity of microorganisms
the level of hygiene
the delay before packaging
the temperature
the properties of the packaging material,
e.g. permeability
4 the free gas volume of the package
4 the gas mixture.
Accumulated know-how supports
choice of application solution
In order to be able to recommend the right
MAPAX solution for the application in
question, AGA acts as more than a mere supplier of gas. MAPAX from AGA is based on
close cooperation between the suppliers of the
packaging material, the packaging machines
and the gases.
The purpose of this collaboration between
suppliers is to be able to meet demands for an
efficient and cost-effective packaging of foodstuffs, with retained product quality throughout the entire distribution chain and ending as
an attractive display in the chilled-food counter.
18
The goal of this cooperation, by exploiting
the advantages of MAP technology in the
right way and by adapting methods to each
application, is also to be able to offer solutions
that make it possible for the manufacturer to
develop new products for sale on new markets.
Research generates necessary know-how
Modified atmosphere technology is a fastgrowing field. This is clearly proven by the
intensive research work in progress throughout
Europe. Projects are currently underway, for
instance, at research institutes at Campden RA
in the UK, the Swedish Institute for Food
Research (SIK), the Technical Research Centre
of Finland (VTT), Hochschule Bremerhaven in
Germany and the Institute of Food Technology
in Norway that involve product quality and
product safety within the field of MAP.
AGA works closely with such research institutes. In the laboratories of SIK, for example,
various simulations are carried out to determine
the potential hazards from microorganisms.
Such studies provide the information necessary
for determining safe shelf-life intervals.
Because AGA has access to know-how dealing with how different bacteria are affected by
the combination of temperature/atmosphere
and other such parameters as permeability, a
MAPAX solution can be offered that will
ensure maximum microbiological security for
each foodstuff.
Practical experience gives
confirmed safety solutions
AGA has customers in the food processing
industry round the world. Valuable contacts
have been established with several leading
companies that package their products in
modified atmospheres.
For a number of years, AGA has had the
advantage of accumulating experience and
know-how from applications for which
MAPAX has proved to be the answer. The
collaboration with the food processing industry has contributed greatly to facilitating
the choice of a suitable atmosphere and packaging material for individual applications.
MAPAX offers a complete menu of solutions.
Contents in brief
4 MAP results depend on numerous factors such as
4
4
the properties of the foodstuffs, the packaging and
the gases.
MAPAX is a MAP solution adapted to each
application.
MAPAX is founded on accumulated knowledge
and experience.
19
Meat and Meat Products
The right MAPAX solution suitable for
meat and meat products
Meat and meat products are particularly susceptible to bacterial growth owing to their high
water activity.
Meat is sterile from the start, but when cut
apart, the surfaces exposed to the ambient air
offer excellent breeding grounds for most bacteria. Minced meat is naturally even more exposed. For this reason, hygiene in processing
and prepackaging is vitally important – keeping
tools and equipment clean – to minimize the
introduction of microorganisms into the product.
Carbon dioxide effectively solves
the biggest problem
Carbon dioxide, generally speaking, has a
strong inhibiting effect on the growth of bacteria, of which the aerobic genus Pseudomonas
presents the greatest problem for fresh meat.
Product
Gas mixture
Gas volume
Product weight
80% O2+20% CO2
100-200 ml
100 g meat
2-4 days
5-8 days
50-80% CO2 +
20-50% N2
100-200 ml
100 g meat
7 days
Sausages
20% CO2+80% N2
Sliced cooked
meat products
20% CO2+80% N2
Red meat
Poultry meat
* PVC is being replaced by APET or PS/EVOH
PVdC is being replaced by EVOH or OPA
20
Red meat requires oxygen
A special problem arises with red meats such as
beef in regard to colour changes caused by the
oxidation of the red pigment. The atmosphere
for fresh meat therefore normally contains high
concentrations of oxygen (60–80%) in order to
retain the red colour by ensuring high oxygen
levels in the meat’s myoglobin. Highly pigmented meats such as from beef thus require
higher oxygen concentrations than do low pigmented meats such as pork.
With the right mixtures, the practical shelf-life
of consumer-packed meats can be extended from
2 – 4 days to 5– 8 days at + 4 °C. If master-packs
are used in distribution, high CO2 levels can be
used, thereby increasing shelf-life.
Typical shelf-life
Air
MAP
Typical material*
Typical machine
Storage temp.
OPET/PVdC/PE-PVC/PE
Deep-draw machine
+2 -+3 °C
16 -21 days
OPET/PVdC/PE-PVC/PE
Deep-draw machine
+2 -+3 °C
50-100 ml
100 g prod.
2-4 days 4-5 weeks
OPET/PVdC/PE-PVC/PE
PA/PE
Deep-draw machine
Horizontal flow-pack
+4 -+6 °C
50-100 ml
100 g prod.
2-4 days 4-5 weeks
OPET/PVdC/PE-PVC/PE
Deep-draw machine
+4 -+6 °C
Meat products have a different microflora
Deterioration of meat products are most commonly caused by microbial spoilage. Due to the
processing operations, for instance marinating,
drying, smoking, fermentation, curing and
cooking, the microflora in meat products differs
from that in raw meat and the spoilage mechanisms are thereby different.
This affects the gas composition used in the
package. In order not to turn the products sour,
the concentration of carbon dioxide is usually
low (20–50%).
Yeast count log10 (cfu/g)
Before
opening
6
5
3 days
after opening
4
Microbiological shelf-life
of chicken at different
atmosphere/temperature
combinations.
Shelf-life (days)
30
25
A = 100% CO2 1 °C
B = 10 – 30% CO2 rest N2 1 °C
C = Vacuum 1 °C
D = 100% CO2 4 – 6 °C
E = Vacuum 4 – 6 °C
F = 10 – 30% CO2 rest N2 4 – 6 °C
G = Air 1°C
H = Air 4 – 6 °C
20
15
10
5
0
A
B
C
D
E
F
G
H
Shelf-life of poultry is highly affected
Poultry is very susceptible to bacterial spoilage,
evaporation loss, off-odour, discoloration and
biochemical deterioration. The sterile poultry
tissue becomes contaminated during the evisceration process.
The practical shelf-life of gas-packed poultry
is about 16 to 21 days. The head-space volume
should be nearly as large as the product volume.
3
2
1
0
Storage time
MAP
AIR
9 days
MAP
AIR
21 days
CO2 also has residual inhibitory effect after opening the
MAP package. The yeast count of cooked minced meat
steaks immediately after opening and after three days from
the opening. MAP = 20% CO2 + 80% N2.
Air = conventional air package
Contents in brief
4 Carbon dioxide inhibits the growth of the main
4
4
spoilage organism, Pseudomonas, for fresh meat.
Oxygen preserves the red colour of meat.
Gas-packaged poultry can retain its high quality for
about three weeks.
21
Fish and Seafood
The right MAPAX solution suitable
for ½sh and seafood
Fresh fish rapidly lose their original quality due
to microbial growth and enzymatic processes.
The sensitivity of fish and seafood is caused by
their high water activity, neutral pH (at which
microorganisms thrive best) and the presence
of enzymes, which rapidly undermine both
taste and smell. The breakdown of proteins by
microorganisms gives rise to unpleasant
odours. The oxidation of unsaturated fats in
high-fat fish such as salmon, herring and
mackerel also results in unappetizing taste and
smell. Fish such as herring and trout can turn
rancid even before microbial deterioration is
detectable.
In order to maintain the high quality of
fresh fish products, it is absolutely necessary to
maintain the temperatures as close to 0 °C as
Quality
High
Low
Air
MAP
Time
Fish such as cod and plaice can retain their high quality
twice as long in the correct modified atmosphere at 0 °C.
22
possible. In combination with the right gas
mixture, shelf-life can be extended a few important extra days. One condition, naturally, is
an unbroken chain of refrigeration. Cod, flounder, plaice, haddock and whiting are examples
of fish that can be stored at 0 °C twice as long
in a modified atmosphere as in air.
Carbon dioxide a prerequisite
for retained quality
The presence of carbon dioxide is necessary to
inhibit the growth of common aerobic bacteria
such as Pseudomonas, Acinetobacter and
Moraxella. At levels above 20% in big enough
package volumes, growth is primarily inhibited
in fish because carbon dioxide reduces the pH
level of the tissue surface. The carbon dioxide
concentration is normally 50% in practical
situations.
Depending on the storage temperature
(0 –2 °C), modified atmosphere packaging prolongs the shelf-life by 3 to 5 days compared
with the shelf-life of raw fish in a tray with
film overwrap.
Excessively high concentrations can produce
undesirable after-effects in the form of lost
tissue liquid or, in the case of crabs, an acidic
or sour taste.
Product
Gas mixture
Fatty fish
60 -70% CO2+
30 -40% N2
Lean fish
Cooked
fish products
Gas volume
Product weight
Typical shelf-life
Air
MAP
Typical material*
Typical machine
Storage temp.
200 -300 ml
100 g fish
3 - 5 days
5 - 9 days
OPET/PVdC/PE-PVC/PE
Deep-draw machine
+0 -+3 °C
30 -40% O2+
30 -70% CO2+
0 -30% N2
200 -300 ml
100 g fish
3 - 5 days
5 - 9 days
OPET/PVdC/PE-PVC/PE
Deep-draw machine
+0 -+3 °C
20% CO2+80% N2
50 -100 ml
100 g prod.
2 -4 days
4 -5 weeks
OPET/PVdC/PE-PVC/PE
Deep-draw machine
+4 -+6 °C
* PVC is being replaced by APET or PS/EVOH
PVdC is being replaced by EVOH or OPA
Oxygen keeps colour
Oxygen can be used as a component of a modified atmosphere to avoid colour changes and
pigment fading in fish and seafood. The gas is
also used to prevent the growth of anaerobic
microorganisms such as Clostridium, which
can produce toxin. The risk, however, for
Clostridium growth in correctly modified
atmosphere packed fish with short shelf-life
is negligible. If the temperature is kept below
+3 °C, there can be no growth.
To combat rancidity, oxygen should not
be used in packages of high-fat fish. In such a
case, nitrogen is more suitable.
Contents in brief
4 Fresh fish have an extremely short shelf-life.
4 CO2 levels of 40–60% in suitable packages are
4
normally used.
MAP normally gives 20–50% extended shelf-life
compared to air.
23
Dairy Products
The right MAPAX solution suitable
for dairy products
Microbial growth and rancidity are the primary causes of the quality deterioration in
dairy products.
The type of breakdown depends on the
characteristics of the particular product. Hard
cheeses with relatively low water activity are
normally affected by the growth of moulds,
whereas products with high water activity such
as cream and soft cheeses are more susceptible
to fermentation and rancidity.
Lactobacillus, which is much used in the
dairy industry, may also be a problem by turning products sour by lowering their pH. This
may further be intensified by the fact that
cottage cheese packages, for example, contain
incorrect gas atmospheres with excessive levels
of carbon dioxide.
Mould prevented by carbon dioxide
In the packaging of hard cheese, carbon dioxide
is used first and foremost. It effectively stops or
reduces microbial activity and contributes to
retaining texture. Carbon dioxide concentrations
of 20% already strongly affect the growth of
mould fungi. Lactic acid bacteria, a natural
constituent of cheese, is affected very little by
the surrounding atmosphere (see below).
Soft cheeses are also packaged in atmospheres of increased carbon dioxide levels and
low oxygen levels to inhibit bacterial growth
and rancidity.
Inhibition for various bacteria in 100% CO2 atmosphere.
Bacillus cereus
Yersinia frederiksenii
Staphylococcus aureus
Clostridium sporogenes
Citrobacter freundii
Escherichia coli
Streptococcus faecalis
Yersinia enterocolitica
Brochothrix thermosphacta
Lactobacillus viridescens
Lactobacillus plantarum
0
24
20
40
60
80
Inhibition %
Product
Gas mixture
Gas volume
Product weight
Typical shelf-life
Air
MAP
Typical material*
Typical machine
Storage temp.
Hard
cheeses
80 -100 % CO2+
0 -20% N2
50 -100 ml
100 g cheese
2-3 weeks 4-10 weeks
OPA/PE-PA/PE
PA/PE
Deep-draw machine
Horizontal flow-pack
+4 -+6 °C
Hard
cheeses
(sliced)
80 -90 % CO2 +
10 -20 % N2
50 -100 ml
100 g cheese
2-3 weeks 4-10 weeks
OPA/PE-PA/PE
PA/PE
Deep-draw machine
Horizontal flow-pack
+4 -+6 °C
Soft
cheeses
20 -40% CO2+
60 -80% N2
50 -100 ml
100 g cheese
4-14 days 1-3 weeks
OPA/PE-PA/PE
Deep-draw machine
Horizontal flow-pack
+4 -+6 °C
* PVC is being replaced by APET or PS/EVOH, PVdC is being replaced by EVOH or OPA
In packaging for hard cheeses, the carbon
dioxide level is up to 100% and for soft cheeses,
the level is usually restricted to 20–40%. The
reason for this is to prevent the package from
collapsing under atmospheric pressure as the
carbon dioxide dissolves into the contained
water.
Value-added cheese, such as grated or sliced
cheddar, are also packed in modified atmosphere. Grated cheese is usually packed in an
atmosphere of 70% N2 and 30% CO2. The use
of only 30% CO2 avoids package collapse.
Nitrogen stops sour cream
Cream and dairy products containing cream
rapidly turn sour in carbon dioxide atmospheres. The gas is therefore replaced by nitrogen. By keeping out oxygen, nitrogen prevents
rancidity and the growth of aerobic bacteria.
Cultured products a new application
Cultured products, such as cottage cheese and
yoghurt, have not been packed in modified
atmospheres until recently. But the demands for
longer lives has led to its use.
centrations of between 20 and 100% are used in
retail packaging.
Nitrogen replaces carbon dioxide in packages
containing products that easily turn sour,
e.g. cream.
The shelf-life of cottage cheese packed under
carbon dioxide can be extended by a week.
Contents in brief
4 Cheeses are particularly susceptible to mould growth.
4 Growth is inhibited by carbon dioxide. Con4
25
Fruits and Vegetables
The right MAPAX solution suitable
for fruits and vegetables
Packaging material of the correct permeability
must be chosen for the successful MAP of fresh
produce. If produce is sealed in an insufficiently permeable film, undesirable anaerobic
conditions (<1% O2 and >20% CO2) will develop with subsequent deterioration in quality.
Conversely, if produce is sealed in a film of
excessive permeability, little or no modified
atmosphere will result and moisture loss will
also lead to accelerated deterioration in quality.
Examples of materials that can be used for
MAP of fresh produce are microporous film
or LDPE/OPP.
The limits of optimal gas mixtures for fruits and vegetables.
Optimal equilibrium modified atmosphere
prolongs shelf-life
The key to successful MAP of fresh produce is
to use a packaging film of correct intermediary
permeability where a desirable equilibrium
modified atmosphere (EMA) is established
when the rate of oxygen and carbon dioxide
transmission through the pack equals the produce respiration rate. Typically, optimal EMAs
of 3–10% O2 and 3–10% CO2 can dramatically
increase the shelf-life of fruits and vegetables.
The EMA thus attained is influenced by
numerous factors such as respiration rate,
25
20
< 2 days
15
3 days
6 days
10
10 days
5
> 14 days
5
20
Typical machine
2 5 % O2
Gas volume
Product weight
Lettuce
3-10 % CO2+3-10% O2+
80-94%N2
100 -200 ml
100 g prod.
2-5 days
5-10 days
LDPE/OPP
Horizontal flow-pack
+3-+5 °C
Mushroom 3-10 % CO2+3-10% O2+
80-94%N2
100 -200 ml
100 g prod.
2-3 days
5-6 days
LDPE/OPP
Deep-draw machine
Horizontal flow-pack
Deep-draw machine
+3-+5 °C
Pre-peeled
potato
100 -200 ml
100 g prod.
0.5 hours
Vacuum
2 days
10 days
PVdC is being replaced by EVOH or OPA
Typical material*
15
Gas mixture
40-60% CO2+
40-60%N2
Typical shelf-life
Air
MAP
10
Product
* PVC is being replaced by APET or PS/EVOH
26
% CO2
OPET/PVdC/PE-PVC/PE Deep-draw machine
PA/PE
Snorkel-vac
Storage temp.
+3-+5 °C
temperature, packaging film, pack volume, fill
weight and light. Respiration rate is affected by
the variety, size, maturity and severity of produce preparation. Consequently, determination
of the optimal EMA of a particular produce
item is a complex problem that can only be
solved through practical experimental tests.
Beneficial MAP of fresh produce can be
attained by either sealing the produce in air or
gas flushing with 3 – 10% O2 /3 – 10% CO2/
80 – 90% N2. As previously explained, modified atmospheres evolve within an air-sealed
pack because of produce respiration. There
may be circumstances, however, when it is
desirable to gas flush so that a beneficial EMA
is established more quickly. For example,
enzymic browning of salad vegetables can be
delayed by gas flushing compared with air
packing. Practical experimental tests should
be undertaken to demonstrate this.
Different conditions may apply for peeled
potatoes and apples, which should not be
packed with oxygen because of enzymic
reactions that bring about brown-discolouring.
Pre-peeled potatoes, for example, can be packed
in 20% CO2 + 80% N2 with a prolonged shelflife from 0.5 hour to 7–8 days at +4 to +5 °C.
Contents in brief
4 Fruits and vegetables respire in packages.
4 EMAs are generated within sealed produce packs.
4 Good hygiene and handling, correct temperature
and appropriate packaging materials are vital for
successful MAP.
Brian P.F. Day M.Sc.
Senior Research Officer,
Department of Product and
Packaging Technology, Campden
Food and Drink Research
Association
“The effective MAP of fresh produce
is complicated by the fact that, unlike
other chilled perishable foods, fresh
produce continues to respire after
harvesting. The depletion of oxygen
and elevation of carbon dioxide are
natural consequences of respiration
when fresh produce is stored in a
sealed package. Such modification of
the atmosphere results in a decrease in
the respiration rate resulting in an
extended quality shelf-life.
The principal spoilage mechanisms
affecting whole and prepared fresh
produce (slice, cut, peeled, etc.) are
microbial growth, enzymic browning
and moisture loss. Correct use of MAP
is very effective at inhibiting these
spoilage mechanisms in addition to
extending shelf-life by reducing
respiration, ripening, softening and
chlorophyll breakdown of fresh
produce.
Only fruits and vegetables of the
highest initial quality should be used
for MAP. Hygienic and gentle
handling during harvesting, storage,
preparation, packaging and distribution, at the correct chilled temperature, is of vital importance in ensuring
the safety and extended shelf-life of
modified atmosphere packaged
produce.”
27
Dry Foods and Bakery Products
The right MAPAX solution suitable for
dry foods and bakery products
Dry foodstuffs such as flour, potato chips,
peanuts, coffee and spices as well as powdered
milk and cocoa products contain more-or-less
unsaturated fats. These products are thus sensitive to oxidation and rancidity. High quality
shelf-life is therefore totally dependent on the
oxygen concentrations in the packaging. Even
small amounts of oxygen may destroy quality
and make the products impossible to sell.
Packages containing particularly sensitive dry
foodstuffs such as powdered milk for babies
should have oxygen levels of less than 0.2%.
The detrimental processes can be effectively
inhibited by replacing the oxygen in the package with nitrogen or carbon dioxide. A prerequisite for maintaining an optimal modified
atmosphere is naturally that the package is
provided with oxygen and
moisture barriers.
How the products were
initially protected from
oxygen is also
decisive. It may be
necessary to reduce
the oxygen level in
the processing of the
product.
28
Increase in mould-free shelf-life (%)
500
400
300
200
100
0
20
40
60
80
100
Average carbon dioxide concentration (% by volume)
Product
ERH* Storage
(%) temp (°C)
Product
ERH* Storage
(%) temp (°C)
l
Madiera cake
85
21
l
Fruit pies
95
l
Madiera cake
83
27
l
Rye bread slices
92
21
l
Crumpets
94
27
l
Part baked rolls
88
21
l
Part baked bread 91
21
*ERH=Equilibrium Relitive Humidity
27
Carbon dioxide slows mould
growth on bread
The main spoilage factors for bakery products
are mould growth and chemical breakdown.
Fermentation may cause problems in filled
bakery. Since the water activity of bakery
products is low, the growth of microorganisms
other than mould is seldom a problem.
Mould growth is an aerobic microorganism, it can be effectively controlled by carbon
dioxide together with low residual oxygen
levels ( less than 1% ), which subsequently
Product
Gas mixture
Gas volume
Product weight
50-70% CO2+
30-50% N2
50 -100 ml
100 g prod.
3 -5 days
20-40% CO2+
60-80% N2
50-100 ml
100 g prod.
max.
some weeks
even
one year
Rye wheat
bread
20-40% CO2+
60-80% N2
50-100 ml
100 g prod.
max.
some days
2 weeks
Prebaked
bread
80-100% CO2+
0-20% N2
50-100 ml
100 g prod.
5 days
20 days
Pies
Cakes
Typical shelf-life
Air
MAP
2 - 3 weeks
Typical material*
OPET/PVdC/PE-PVC/PE
PA/PE or OPET/PVdC/PE
OPET/PVdC/PE-PVC/PE
OPET met./PE
OPET/PVdC/PE-PVC/PE
PA/PE or OPET/PVdC/PE
OPET/PVdC/PE-PVC/PE
PA/PE or OPET/PVdC/PE
Typical machine
Storage temp.
Deep-draw machine
Horizontal flow-pack
+4 -+6 °C
Deep-draw machine
Flow-pack
+20 -+25 °C
Deep-draw machine
Flow-pack
+20 -+25 °C
Deep-draw machine
Flow-pack
+20 -+25 °C
* PVC is being replaced by APET or PS/EVOH
PVdC is being replaced by EVOH or OPA
100
extends shelf-life by many valuable days. MAP
is especially suitable for rye bread, sweet
bakery products, different pies and prebaked
bread.
For Danish pastry and other iced bakery
products, excessive levels of carbon dioxide
can worsen the appearance of the icing by dissolving into the contained fat and causing it to
“melt away”. If the carbon dioxide concentration is balanced by nitrogen, the product’s
appearance remains unchanged.
The loss or adsorption of moisture in bakery
products is prevented by a barrier material.
3
O2
Time (days) to reach mould
development on toast at
various atmospheres and
+20 °C. The toast was
initially infected by mould.
5
99% N2 + 1% O2
99% CO2 + 1% O2
Contents in brief
4 Oxygen concentrations, even in small amounts, can
4
4
cause dry foodstuffs to oxidize.
Oxygen is replaced by nitrogen or carbon dioxide to
maintain high quality.
Carbon dioxide inhibits the growth of mould on
bread.
29
Prepared Foods
The right MAPAX solution suitable
for prepared foods
The deterioration of prepared foods varies considerably with the product. If meat is one of the
main ingredients as in ravioli or lasagna, it is
spoiled differently than, for instance, the pasta.
A major difficulty associated with prepared
foods is the introduction of microbial contamination during the manufacturing process. This
therefore places stringent demands on hygiene
as well as on the raw materials during the
production process.
The most serious breakdown processes are
caused by the growth of microorganisms and
by oxidation and sometimes also by staling
– leading to rancidity, discoloration and loss of
taste. A fresh pizza, for example, left out in the
open air at +4 to +6 °C, is spoiled in about a
week. High quality can be kept extra weeks by
packaging the product in a modified
Multi-ingredient products have
special demands
Each product in the area of prepared foods
represents a complex problem. Particularly
difficult are such varying combinations as
Product
Gas mixture
Gas volume
Product weight
Pizza
30-60% CO2+
40-70% N2
50-100 ml
100 g prod.
1-2 weeks
2-5 weeks* OPET/PVdC/PE-PVC/PE Deep-draw machine
OPA/PE
Horizontal flow-pack
+4 -+6 °C
French
fries
70-80% CO2+
20-30% N2
50-100 ml
100 g prod.
3 - 4 days
1-3 weeks
OPET/PVdC/PE-PVC/PE Deep-draw machine
+4 -+6 °C
100% N2
50-100 ml
100 g prod.
1-2 weeks
2 -3 weeks
OPET/PVdC/PE-PVC/PE Deep-draw machine
+4 -+6 °C
50-100 ml
100 g prod
1-2 weeks
4-5 weeks
OPET/PVdC/PE-PVC/PE Deep-draw machine
OPA/PE
flow-pack
+4 -+6 °C
Salads
with sauce
Cooked minced 20% CO2+80% N2
meat products
(steaks,balls)
** PVC is being replaced by APET or PS/EVOH
PVdC is being replaced by EVOH or OPA
30
atmosphere having a low oxygen concentration
and high carbon dioxide level. In the case of
pizza, the concentration of oxygen should be
less than 1%.
The relationship between carbon dioxide
and nitrogen in prepared food packages mainly
depends on the moisture content of the product,
but also on the composition of the food. This
determines the speed of microbial growth,
oxidation and enzymatic activity. The higher the
water activity, the higher the carbon dioxide
concentration in the package.
Typical shelf-life
Air
MAP
Typical material**
Typical machine
Storage temp.
Growth rate
pH value
acid
neutral
basic
Growth of microbes as a function of the medium.
sandwiches, filled pasta, salads, pizza and
spring rolls.
Since several different ingredients, each
with its own special inherent properties, make
up the product, in-depth know-how is required
regarding the right gas mixture that will best
inhibit deterioration and maintain quality.
Modified atmosphere packaging is an important hurdle and safety measure, since prepared
foods in the wrong environments can spoil
very fast, for example, such as is the case with
food products having neutral pH value (see
above).
Contents in brief
4 Prepared foods constitute a complex area owing to
4
4
internal differences in the process of deterioration
and in final preparation.
Water activity and food composition are decisive
factors with regard to shelf-life.
Products with many various ingredients are
particularly susceptible to spoilage.
the components and gas mixture
should be chosen in such a way
that MAP is optimal for every
component.
The inhibition of mould
growth is best assured by using
carbon dioxide mixed with nitrogen. A carbon dioxide concentration of 20–30% mixed with
Raija Ahvenainen, Ph.D., Senior nitrogen gas is sufficient and
even optimal for many products.
Scientist.
VTT Food Research Laboratory, Finland With regard to pizza and other
baked products (pies etc.), at
“MAP is an effective, economical least 20%, but preferably more
and optimal method in improving carbon dioxide, is required. The
the quality and shelf-life of most residual oxygen concentration
prepared foods. MAP has, partic- should be below 1% immediately
ularly with regard to the microafter packaging.
biological deteroration of preAs far as packaging material is
pared foods, a most remarkable
concerned, the materials convenretarding effect on yeast and
tionally used in vacuum packmould growth and naturally on
aging by deep-draw packaging
the sensory changes caused by
machines, and in air packaging
these microbes.
by different tray systems are also
The optimal gas composition is suitable for MAP of prepared
very dependent on the product,
foods. No high barrier materials
and it should be tested when
including an EVOH or a PVdC
starting to package a new
layer are necessary, but the microproduct in gas, even when some
wavability of the packaging
changes in the recipe are made.
materials is becoming more and
As for multi-component foods,
more important.”
31
Future
Why does MAP represent the food
preservation technology of the 90s?
Developments internationally are clear. Modified atmospheres have a definite future. In the
UK, which is the oldest and, up to now, biggest
market for MAP products in Europe, Marketing
Strategies for Industry (MSI) predicts that MAP
use will increase dramatically between 1993 and
1995. The 1.93 billion packages with modified
atmosphere sold in the UK in 1992 is expected
to increase by a billion packages annually up
to 1995.
In the USA, the MAP trend is somewhat
more recent, but the American market is expected to swiftly pass the European market
when it comes to exploiting the technology.
Market studies reveal that the US market for
MAP products will grow, by the end of 1993,
to three billion units.
Billion packages
5
4
3
2
1
1992
MAP packages sold in UK.
32
1995
Modified Atmosphere Packaging
– a proven recipe
The packaging of foodstuffs in modified atmosphere increases the chances of a sale. Food
stores will keep customers who might otherwise
“defect” to shops that sell fresh fish, fresh meat
and other fresh produce over the counter. A few
days or even weeks of extra shelf-life also opens
the door to the sale of new products on new
markets.
One example to be mentioned is the great
success experienced by the chain Marks &
Spencer in the UK in recent years involving
fresh meats and meat products, seafood, pasta,
poultry, bread and bakery products.
The success story of MAP continues round
the world. Today, no other method for enhancing shelf-life quality can offer so many benefits
throughout the entire processing chain as does
modified atmosphere packaging. Modified
atmosphere technology provides careful treatment of foodstuffs and retains their inherent
quality as long as possible.
Furthermore, MAP technology is cost-effective. Costs for equipment, packaging material
and gases can be kept to a minimum, and a
packaging machine can be used for many different products.
MAPAX – the optimal solution of MAP
AGA, one of the world’s leading suppliers of gas
to the food industry, invites you to discuss the
many advantages of modified atmosphere
technology – designated MAPAX. The overall
concept is adapted to every application and is
based on the necessary data about foodstuffs,
gases and packaging.
The choice of application solution arises from
a vast accumulation of knowledge and experience.
AGA works closely with research institutes
throughout Europe as well as with large-scale
worldwide food industries.
AGA’s access to in-depth know-how and
practical experience gives rise to confirmed
solutions for each foodstuff and guarantees a
cost-effective packaging of products, with retained
quality throughout the entire distribution chain
and ending as an attractive display in the chilledfood counter.
It is therefore quite natural that the growth of
modified atmosphere technology is substantial.
This not only applies to large-scale food
industries, but also to a very large extent to
smaller manufacturers, distributors, catering
companies and restaurants.
AGA invites you to discuss the many advantages of modified atmosphere technology.
Contents in brief
4 The use of MAP will increase dramatically in future.
4 MAPAX from AGA is shaped by customer
4
demand.
MAPAX is used more and more by large-scale
food industries as well as by smaller producers,
wholesalers and retailers.
33
Glossary
A
C
Acinetobacter
A genera of common food-borne bacteria.
They are classified as aerobic Gram-negative
short rods.
Aerobic organism
An organism that normally grows in the
presence of air (20% oxygen).
Anaerobic organism
An organism that normally grows in the absence
of air (20% oxygen) or oxygen. Anaerobes can
be ‘strict’ (obligate) anaerobes, i.e. they can be
killed by oxygen, or ‘facultative’ anaerobes, i.e.
they can grow under either aerobic or
anaerobic conditions.
Anti-fogging properties
Film manufacturers produce a high surface
tension with hydrophilic properties that allows
moisture to completely wet the surface in order
to avoid fogging.
CA
Controlled Atmosphere
Carbon dioxide
CO2 has a slightly acidic odour. It dissolves
easily in water and thereby inhibits growth of
many microorganisms. Air contains approximately 0.03% carbon dioxide.
Catalyst
A substance that regulates the rate of a chemical
reaction and itself remains unchanged.
Clostridium
A genus of which the bacteria are classified as
Gram-positive rods, anaerobic endospore
formers with a fermentative mode of metabolism.
Controlled atmosphere
The atmosphere surrounding a food is changed
and is then controlled during storage.
B
Bacteriostatic effect
Capable of inhibiting bacterial growth without
killing.
Biochemical process
Process or phenomenon in living organism or in
biological system described in chemical terms.
34
E
EMA
Equilibrium Modified Atmosphere
Enzymatic reaction
Chemical reactions catalysed by enzymes.
Enzyme
Globular protein that is the catalyst of a biological system.
ERH
Equilibrium Relative Humidity.
F
Fermentation
Anaerobic energy-yielding metabolism of cells.
G
Gas flushing
Flushing with gas or a gas mixture to establish
a modified atmosphere.
I
Inert gas
A gas that does not react with other substances
under normal temperatures and pressures.
L
Lactic acid bacteria
Gram-positive bacteria, usually non-motile,
nonsporulating bacteria that produce lactic
acid as a major or sole product of
fermentativemetabolism. All rod-shaped lactic
acid bacteria are placed in one genus called
Lactobacillus.
M
MAP
Modified Atmosphere Packaging. This means
altering the composition of the atmosphere
inside a package from that of normal air .
MAPAX™
MAPAX is a tailor-made MAP solution based
on data about the food, the gases and the
packaging.
Master-pack
Consumer packages (overwraps) are packed in
a big flexible pack that is gas flushed.
Membrane
A membrane consists of numerous layers of
very thin polymer film, bundled into fibres. It
is used to produce nitrogen on-site by exploiting the variations in velocity at which different
gas molecules pass through polymer materials.
Mesophilic bacteria
Organisms living in the temperature range
around that of warm-blooded animals. This
means those that grow well between 20 °C and
45 °C.
Microorganism
All microscopic forms of life, which includes
such forms as bacteria, fungi, viruses, Protozoa
and algae.
35
Glossary
Modified atmosphere
An atmosphere differing from that of normal
air. Normally, the oxygen content is reduced
and the carbon dioxide content is increased.
Moraxella
A genus of aerobic Gram-negative rod or
coccoid-shaped bacteria that are present in
mucous membranes of man and/or animals.
Mould
Aerobic food-spoilage microorganisms. They
tolerate low water-activity and low pH.
Myoglobin
The principal pigment in fresh meat. The form
it takes is of prime importance in determining
the colour of the meat.
N
Nitrogen
N2 is an inert gas with low solubility in water.
Air contains approximately 78% nitrogen.
Nutritional content
Expresses the amount of nourishing compounds, e.g. carbohydrates, fats, proteins and
vitamins.
O
Oxidation
This means the removal of an electron, whereas
reduction means the addition of an electron. In
36
general, the process of removing hydrogen
atoms or of adding oxygen atoms is referred to
as oxidation.
Oxygen
O2 is a very reactive gas with low solubility
in water. Air contains approximately 21%
oxygen.
P
pH
Express acidity (pH 0–6), neutrality (pH 7)
and alkalinity (pH 8–14).
PSA
Pressure Swing Adsorption. This technology is
used to produce nitrogen on-site. It is based on
the ability of activated carbon under certain
conditions to capture and retain oxygen from
the air, while allowing nitrogen to pass
through.
Protein
Macromolecules built up of amino acids with
peptide bonds.
Pseudomonas
A genus of an aerobic Gram-negative rodshaped bacteria, ecologically important
organisms in soil and water owing to their
large capacity for mineralization of organic
matter.
Psychrophilic bacteria
These bacteria have the ability of growing at
low temperatures, i.e. 0 °C to 5 °C.
R
Rancidity
Oxidation of lipids.
Respiration
Aerobic energy-yielding metabolism of cells.
S
T
Thermophilic bacteria
Organisms that grow at elevated temperatures,
i.e. above 55 °C.
W
Water activity
aw. The ratio of the water vapour pressure of a
material to the vapour pressure of pure water
at the same temperatue.
Shelf-life
The duration of that period between the
packing of a product and its use for which the
quality of the product remains acceptable to
the product user.
Shelf-life technology
The methods for enhancing shelf-life.
Sous vide
Sous vide technique means preparing of the
meal at low temperature (70 to 80 °C),
vacuum packaging and quickly chilling down
to +2 to +4 °C.
37
Reference Literature
Ahvenainen, Raija. “Gas packaging of chilled
meat products and ready-to-eat foods.” Diss.,
Helsinki University of Technology, November,
1989.
Campden Food and Drink Research
Association. “Guidelines for the Good
Manufacturing and Handling of Modified
Atmosphere Packed Food Products.”
Compiled by B.P.F. Day. July, 1992.
Chilled Foods: The State of the Art, ed. T.R.
Gormley. Elsevier Science Publishers Ltd,
1990. ISBN: 1-85166-479-3.
Controlled/Modified Atmosphere/Vacuum
Packaging of Foods, ed. Aaron L. Brody.
Trumbull: Food & Nutrition Press, Inc., 1989.
ISBN: 0-917678-24-9.
Hirsch, Arthur. Flexible Food Packaging:
Questions and Answers. AVI, 1991. ISBN:
0-442-00609-8.
Jenkins, Wilmer A., and James P. Harrington.
Packaging Foods With Plastics. Technomic
Publishing AG, 1991. ISBN: 87762-790-8.
Modified Atmosphere Packaging of Food, ed.
B. Ooraikul, M.E. Stiles. Ellis Horwood Ltd,
1991. ISBN: 0-7476-0064-3.
Paine, Frank A., and Heather Y. Paine. A
Handbook of Food Packaging, 2nd ed.
Glasgow: Blackie Academic & Professional,
1992. ISBN: 0-216-93210-6.
Principles and Applications of Modified
Atmosphere Packaging of Foods, ed. R.T.
Parry. Blackie Academic & Professional,
1993. ISBN: 0-7514-0084 X.
White, Ray. Developments in modified
atmosphere and chilled foods packaging: A
literature review. Pira International, 1992.
ISBN: 0-902799-72 X.
Sources of information.
The diagrams and illustrations in this book are based on our own data or on information found in the reference literature.
38
Argentina
AGA S.A.
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Fax +54/1/724-8881
Austria
AGA Ges.m.b.H.
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AGA nv/sa
Phone +32/2 673 99 09
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Fax +45/32 83 66 01
Dominican Republic
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Fax +593/2 676 758
Estonia
AS Eesti AGA
Phone +372/6 504 500
Fax +372/6 504 501
Finland
Oy AGA Ab
Phone +358/(0)10 2421
Fax +358/(0)10 242 0311
France
AGA s.a.
Phone +33/1/47 14 20 80
Fax +33/1/47 08 68 33
Germany
AGA Gas GmbH
Phone +49/(0)40/42105-0
Fax +49/(0)40/42105-341
Hungary
AGA Gáz Kft.
Phone +36/1/280 19 42
Fax +36/1/280 20 09
Iceland
ÍSAGA hf.
Phone +354/577 3008
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Italy
AGA S.r.l.
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Latvia
AGA SIA
Phone +371/7 325 191
Fax +371/7 322 299
Lithuania
AGA UAB
Phone +370/2 701 190
Fax +370/2 701 191
Mexico
AGA S.A. DE C.V.
Phone +52/5/565 55 99
Fax +52/5/390 51 66
Netherlands
AGA Gas B.V.
Phone +31/20/435 3535
Fax +31/20/435 4035
Norway
AGA AS
Phone +47/22 02 76 00
Fax +47/22 02 78 04
Peru
AGA S.A.
Phone +51/1/4 200 030
Fax +51/1/4 292 051
Poland
AGA Gaz Sp.z o.o.
Phone +48/3912 3239
Fax +48/3912 05 26
Puerto Rico
AGA Puerto Rico Corp.
Phone +1/787 754 7445
Fax +1/787 751 6785
Romania
S.C. AGA Gaz S.R.L.
Phone +40/1 322 4813
Fax +40/1 322 3059
Russia
AGA AB, Moscow repr.
Phone +7/095/956 1949
Fax +7/095/956 1948
Slovakia
AGA GAS spol. s r.o.
Phone +421/(0)7/392 575
Fax +421/(0)7/392 572
Spain
AGA S.A.
Phone +34/1-302 6243
Fax +34/1-302 2728
Sweden
AGA Gas AB
Phone +46/(0)8/706 95 00
Fax +46/(0)8/628 23 15
Switzerland
AGA AG
Phone +41/(0)61/826 72 00
Fax +41/(0)61/826 72 01
Ukraine
AGA AB, Ukrainian repr.
Phone +380/(0)562/29 97 30
Fax +380/(0)562/34 56 33
United Kingdom
AGA Gas Ltd
Phone +44/(0)1203/653 200
Fax +44/(0)1203/650 373
Uruguay
AGA S.A.
Phone +598/2/920 102
Fax +598/2/920 106
USA
AGA Gas, Inc.
Phone +1/216/642-6600
Fax +1/216/573 7870
Venezuela
AGA Gas C.A.
Phone +58/(0)2/907 6888
Fax +58/(0)2/907 6817
“MAP is an effective, economical
and optimal method....”
“In future, consumers will demand food products of high
quality that are natural, fresh and minimally processed.
Modified atmosphere packaging, MAP, has a role to play
for better product quality with good food safety and shelflife compared with today’s products.”
Ulf Rönner, Ph.D., Senior Scientist.
SIK, The Swedish Institute for Food Research.
“Correct use of MAP is very effective at inhibiting spoilage
mechanisms affecting whole and prepared fresh produce,
which continues to respire after harvesting.
MAP extends shelf-life by reducing respiration, ripening,
softening and chlorophyll breakdown.”
Brian P.F. Day, M.Sc., Senior Research Officer.
Department of Product and Packaging Technology,
Campden Food and Drink Research Association, UK.
AGA AB, S-181 81 Lidingö, Sweden
Phone +46/(0)8/731 10 00. Fax +46/(0)8/765 04 68.
www.aga.se
FOO-317en-1-9707-2000
Raija Ahvenainen, Ph.D., Senior Scientist.
VTT, Food Research Laboratory, Finland.
ARMANDT & CO BBN
“MAP is an effective, economical and optimal method in
improving the quality and shelf-life of most prepared foods.
MAP has a most remarkable retarding effect on yeast and
mould growth and naturally on the sensory changes caused
by these microbes.”